With tolls set to return to the Cross City Tunnel, motorists will first be inconvenienced by changes to traffic flow.

Sydney drivers to feel squeeze

Motorists will be dealt a double blow this week as the toll-free period on the Cross City Tunnel ends and one of the city's most choked roads is reduced to one general-traffic lane.

Three days before motorists resume paying $3.56 for a one-way trip through the tunnel, the most controversial road closures will be felt most acutely today.

William Street was reduced to one general lane for traffic and a T2 lane - for buses, taxis and cars with at least two passengers - city-bound between Forbes and College streets on Saturday. The same lane rearrangements were applied to eastbound traffic between College and Palmer streets.

The toll-free period on the tunnel was to end on November 13 but the operators, CrossCity Motorway, extended it by more than two weeks to give motorists more time to try the tunnel.

A spokeswoman for CrossCity Motorway, Amanda Lampe, ruled out another extension of the toll-free period and said the toll would apply from Thursday.

About 20,000 motorists a day were using the tunnel before the toll-free period, but CrossCity Motorway says the tunnel is now averaging 53,000 cars a day.

The free period has drawn complaints from motorists entering the tunnel from the south via the Eastern Distributor.

A $4.50 toll still applies to the 770-metre stretch of distributor that links to the tunnel.

The distributor's owner, Airport Motorway, sent infringement notices to motorists who did not pay their toll but after much criticism it wiped a $10 penalty for toll evasion.

The Opposition Leader, Peter Debnam, said the road changes would be a "nightmare".

"It is again the theft of public roads and you have to ask, 'When is it going to end?"' Mr Debnam said.

"Most of the community angst is over the theft of public roads and I think William Street is going to be a disaster and an even bigger disaster when the toll comes back on because people will stop using the Cross City Tunnel."